It was probably on the 16th day of the month that the Persians made up their minds that something must be done. Unless they acted promptly, they might as well not act at all. #THE PERSIAN FORCE IN THE BATTLE.# The Spartans might be expected at Athens on the 18th or 19th. They arrived there on the 17th, as a fact, making a march rapid beyond expectation. It was probably on the night between the 15th and 16th that the Persian preparations were made. Herodotus knows little about what happened until the armies faced one another for battle. Yet there are indications and omissions in his story which point to the course which events followed. On the day of the battle the Greeks in the valley of Avlona found a Persian army facing them in the southern part of the Marathonian plain. ◆H. vi 111.◆ It was evidently drawn up in battle array, for the Greek formation seems to have been modified to suit that of the enemy.[77] What was this Persian force which faced the Greeks? There are two circumstances in Herodotus’ account which render it practically certain that only a moiety of the land army of the expedition actually fought in the battle. Herodotus never mentions the Persian cavalry as having played any part at all in it. They had been landed in Eubœa at the time of the attack on Eretria. ◆H. vi. 102.◆ Marathon had been chosen as a landing-place, because, says Herodotus, it was suitable for cavalry. Yet in the account of the battle they are never mentioned.[78] Had they been in the battle they must have played a prominent part in it. It must, therefore, be concluded that they were not there. If they were not, where were they? Many conjectures have been made on this subject. It seems almost certain that they were on the fleet; that they had been already embarked, together with a large, if not the larger, part of the Persian army.[79] No rational estimate can, on the extant evidence, place the numbers of those who fought on the Persian side in the actual battle at much above 20,000. It might even be reasonably argued that they did not amount even to that sum. Those numbers grew in the evolution of the tradition, until they reached an enormous magnitude. Herodotus is silent on the subject. He is fond of giving numbers on such occasions. It must be concluded that he was not satisfied with his evidence on this point.[80] Tradition surviving in various authors later than Herodotus gives the number of the Athenians and Platæans at about 10,000 men. It is probable that few had been left in Athens, so that the major part of the levy would be present at Marathon. If any conclusion can be drawn from the number of Athenians stated to have been present eleven years later at Platæa it would seem as if tradition did not grossly underestimate the number of those present on the Greek side.[81] #PERSIAN AND ATHENIAN STRATEGY.#